Most families have a fire safety plan that they go over in case of a house fire. But as it turns out, there is something you can do every single night to keep you and your family safer — and it’s really simple.

Getting into the habit of closing bedroom doors before bed is the best thing you can do in case a fire breaks out.

UL, an American safety consulting and certification company, created a controlled burn inside a house for its Close Before You Doze campaign. Firefighters shut one bedroom door and left the other open before setting the house on fire.

After 10 years of research and controlled burns like the one in the below video, the experts have agreed that simply remembering to close your bedroom door can save your life.

As you’ll see in the footage below, the experts walked through the room with the door open and found it completely scorched. But the room that had the door shut is still intact.

The difference is startling. In the first room, everything is melted and destroyed, while in the second room, the bed, stuffed animals, and TV are fine.

“This door sort of acted like a shield,” one of the experts said, and the firefighter agreed. A closed door also gives you time to find an escape route and get out of the house safely.